EP3885085A2 - Stamping tool - Google Patents

Abstract

In a punching tool for cutting plastic-based film elements (12), with a punching die unit (13) which has a plurality of knife carriers (21), on each of which at least one punching knife (25a, 25b) is attached, and with a die (14) which is assigned to the punch unit (13) and is located opposite the latter for receiving the film element (12) to be processed, the punch unit (13) opposite the die (14) during a stroke in a stroke direction (15 ) taking place punching stroke between a starting position (16) and a processing position (17) is mounted relatively movably, wherein the cutting wedges (31) of the punching knives (25a, 25b) in the processing position (17) dip into the film element (12) to be processed and into Depending on the depth of immersion along an edge length of the cutting edge (32), generate a cutting line (43) or a breaking line (44) in the film system (12), see FIG ind the cutting edges (32) of the punching knives (25a, 25b) are contoured so that they each have an edge section (37; 37a, 37b) which is inclined with respect to a reference line (38) at right angles to the stroke direction (15).

Description

The invention relates to a punching tool for cutting PET-based film elements, with a punch unit which has a plurality of knife carriers, on each of which at least one cutting wedge tapering to a cutting edge is fastened, and with a die, which is assigned to the punch unit and which is opposite the same, for Receipt of the film element to be processed, the punch unit being mounted relatively movably between a starting position and a processing position in relation to the die during a punching stroke taking place in one stroke direction, the cutting wedges of the punching knives in the processing position plunging into the film element to be processed and depending on their immersion depth Create a cutting line or a perforation line in the film system along a processing length.

Such punching tools have been known for a long time. The task of such punching tools is to cut large-area film elements made of plastic, which can be, for example, a two-dimensional large-area film or a three-dimensional film element. Such three-dimensional film elements can be, for example, yoghurt pots, which are to be packaged in a certain way after production, for example to be separated or in certain, for example four, Cut out groups of six or eight. Important components of such punching tools are punching knives, which, depending on the depth of immersion in the foil element, generate either a cutting line or, alternatively, a breaking line. If a cutting line is created, the foil element is completely cut. If a break line is created, the foil element to be processed is weakened along this line.

Conventional punching tools, in particular their punching knives, are set up to process, in particular, polystyrene-based film elements. For environmental reasons, such polystyrene-based film elements are increasingly being replaced by other plastic-based film elements, for example PET-based, PLA-based, PP-based film elements. In particular, however, PET-based film elements are tougher compared to polystyrene-based film elements, so that the punching knives are exposed to higher loads.

The object of the invention is therefore to create a punching tool of the type mentioned at the outset, in which the load when processing plastic-based film elements, in particular for the punching knives, is reduced compared to conventional punching tools.

This object is achieved by a punching tool with the features of independent claim 1. Further developments of the invention are presented in the subclaims.

The punching tool according to the invention is characterized in that the cutting edges of the knives are contoured in such a way that they each have an edge section which is inclined with respect to a reference line at right angles to the stroke direction.

The effect of this configuration of the cutting edges of the punching knives is that the cutting line or breaking line is gradually formed when the cutting wedge dips into the film system. The formation of the cutting line or breaking line thus takes place in the manner of a "pulling cut". As a result, if a cutting line is formed, the entire length of the edge is not cut at the same time, which significantly reduces the load on the punching knife. Even with the formation of the breaking lines, perforations are not formed simultaneously over the entire length of the edge, but also gradually.

In a further development of the invention, the cutting wedges of the punching knives are each formed by a wedge inner surface and a wedge outer surface and the die has a die cavity which has a die edge assigned to the wedge inner surface, the wedge inner surface moving during the punching stroke moved along the die edge at a certain distance transversely to the stroke direction. When the cutting wedge dips into the film element to be processed, the cutting wedge is pressed in the direction of the die edge. However, because the cutting edges of the punching knives are designed in such a way that they have an edge section which is inclined with respect to a reference line at right angles to the stroke direction, this pressure is reduced in the direction of the die edge, which reduces the load on the punching knives and thus the quality of the generated cutting or breaking lines increased when cutting into the plastic material.

In a further development of the invention, the cutting edge has two edge sections which are arranged at an angle to one another and which together form a wedge shape. This wedge shape can be produced, for example, in the manner of a diamond cut of the punch knife.

An alternative geometry of the cutting edges of the punching knives are several edge sections which together form a wave-shaped contour. This waveform can be generated, for example, in the manner of a bread knife sharpening of the punching knife.

Alternatively, it is possible for the cutting edge to have several edge sections which together form a zigzag or sawtooth-like contour.

In a particularly preferred manner, the punch unit has several, for example, star-shaped contour punches for punching out a surface section of the film element, the underside of which in the starting position is positioned closer to the die than the cutting edges of the punching knives. During the punching stroke, the contour punches can run ahead of the punching knives and, for example, punch out a star-shaped contour before the punching knives come into contact with the film element.

In a further development of the invention, it is possible that the punching knives are each detachably fastened to a knife seat of the associated knife carrier by means of fastening means, the fastening means being an in particular disk-shaped tuning element inserted between the knife seat and the inner surface of the wedge for setting the distance between the die edge and the wedge inner surface. Once the distance between the wedge inner surface of the punching knife and the die edge has been set using the tuning element, no readjustment or correction of the distance is required when the punching knife is changed, for example as a result of wear, since a newly clamped punching knife always has the maintains the predetermined distance between its wedge inner surface and the die edge, as specified by the tuning element. In a particularly preferred manner, the punch unit has a height adjustment device for adjusting the height of the punch knife between a cutting height position in which the punching knife generates a cutting line during the punching stroke and a perforation height position which is further away from the die compared to the cutting height position in the starting position, in which the Punch knives generate a break line in the form of a perforation line during the punching stroke. In a particularly preferred manner, the height adjustment device is assigned a control device for the individual control of the punching knives in order to move them optionally into the cutting height position or the perforation height position. In this way, an individual punching pattern can be generated, whereby the most varied of assemblies of the film elements to be processed can be carried out with the same punching tool. The height adjustment device can, for example, have a type of switching system that can be controlled by means of the control device, as a result of which the height of the punching knives can be changed. The switching system can be operated fluidically, in particular pneumatically or electrically, for example.

In a particularly preferred manner, the height adjustment device has height adjustment units for the individual adjustment of the height position of the punching knives with respect to the die. A fine adjustment of the height of the punching knife is possible with the height adjustment units. While the height adjustment device ensures that the punching knives are adjusted between the cutting height and the perforation height, the height adjustment unit can be used to achieve a stepless adjustment of the height of the punching knives over a specific adjustment path.

In a particularly preferred manner, the height adjustment units each have one with a base plate of the punch unit connected base body on which the knife carrier with the punch knife is movably mounted in the height direction via an adjustment drive.

The adjustment drive is particularly preferably designed as a spindle drive, whereby a precise height adjustment can be initiated. However, it is alternatively possible to use other types of adjusting drives.

In a further development of the invention, the punch unit has a hold-down device with at least one hold-down device, which fixes the film element to be processed in the processing position on the die.

In a particularly preferred manner, the punch unit has at least one stop element to which at least one counter-stop element is assigned on the die in such a way that the stop element strikes the counter-stop element during the punching stroke to limit the stroke of the punch unit.

In a further development of the invention, the die has at least one contour cavity which interacts with the associated contour punch during the punching stroke and into which the contour punch can be moved, the contour cavity adjoining adjacent knife cavities for the punching knives.

Figur 1

eine perspektivische Darstellung eines bevorzugten Ausführungsbeispiels des erfindungsgemäßen Stanzwerkzeugs,

Figur 2

einen Längsschnitt durch einen Teil der Stanzstempeleinheit von Figur 1,

Figur 3

eine vergrößerte Darstellung der Einzelheit X aus Figur 2,

Figur 4

eine perspektivische Darstellung einer ersten Ausführungsform eines Stanzmessers gemäß dem ersten Ausführungsbeispiel des erfindungsgemäßen Stanzwerkzeugs,

Figur 5

eine perspektivische Darstellung der ersten Ausführung mit zu bearbeitendem Folienelement,

Figur 6

eine perspektivische Darstellung einer zweiten Ausführungsform eines Stanzmessers gemäß eines zweiten Ausführungsbeispiels des erfindungsgemäßen Stanzwerkzeugs,

Figur 7

eine perspektivische Ansicht auf ein Stanzmessermodul mit Messerträger und Stanzmesser sowie Verstellantrieb und

Figur 8

eine Draufsicht auf ein beispielhaft gemäß dem erfindungsgemäßen Stanzwerkzeug bearbeitetes PET-basiertes Folienelement.

In a particularly preferred manner, the contour cavities are each bordered by support sections which support the film element to be processed. The support sections can ensure that the film element to be assembled is adequately supported and does not sag, which would have negative effects on the quality of the cut or perforation. Preferred exemplary embodiments of the invention are shown in the drawing and are explained in more detail below. In the drawing shows:

Figure 1

a perspective view of a preferred embodiment of the punching tool according to the invention,

Figure 2

a longitudinal section through part of the punch unit of FIG Figure 1 ,

Figure 3

an enlarged representation of the detail X from Figure 2 ,

Figure 4

a perspective view of a first embodiment of a punching knife according to the first embodiment of the punching tool according to the invention,

Figure 5

a perspective view of the first embodiment with the film element to be processed,

Figure 6

a perspective view of a second embodiment of a punching knife according to a second embodiment of the punching tool according to the invention,

Figure 7

a perspective view of a punching knife module with knife carrier and punching knife as well as adjusting drive and

Figure 8

a top view of a PET-based film element processed by way of example according to the punching tool according to the invention.

the Figures 1 to 5 , 7th and 8th show a first embodiment of the punching tool 11 according to the invention for cutting plastic-based film elements 12. The punching tool 11 according to the invention is described below by way of example using a three-dimensional PET-based film element 12, which can be, for example, yoghurt cups. It is of course possible to use the punching tool 11 according to the invention to cut or assemble completely different plastic-based film elements 12, for example two-dimensional plastic films. With the punching tool 11 according to the invention it is possible, for example, to assemble two- or three-dimensional PE, PP, PLA or PVC-based film elements.

The aim of the punching processing of the plastic-based, in particular PET-based film elements 12, is to assemble the film elements 12 from a quasi-endless raw strand into individual groups or individual elements. An example is here in Figure 8 a group of four yogurt pots is shown.

As in particular in Figure 1 As shown, the punching tool 11 has a punching die unit 13, which represents the movable part of the punching tool 11. A die 14 for receiving the film element 12 to be processed is arranged opposite the punch unit 13, the punch unit 13 opposite the die 14 during a punch stroke in a stroke direction 15 between a starting position 16 ( Figure 1 ) and a processing position 17 (Figures 2 and 3) is mounted relatively movably.

As in Figure 1 As shown, the punch unit 13 has a base plate 18, which is shown by way of example in a rectangular shape. Several functional components of the punch unit 13 are attached to the base plate 18. To the Functional components include several punching knife modules 19, one of which is exemplified in FIG Figure 7 is shown. The punch knife module 19 has an exemplary cube-shaped base body 20 on which a knife carrier 21 is movably mounted. As in particular in Figure 3 As shown, the knife carrier 21 has a guide section 22 mounted on the base body 20 and a bearing section 23 which forms the free end of the knife carrier 21 and on which a flat and planar knife seat 24 is formed for an associated punching knife 25a. Like in particular the synopsis of the Figures 3 and 7th shows, the punch knife 25a is releasably attached to the associated knife seat 24 by means of fastening means. Fastening screws 26a, 26b are shown by way of example as fastening means, which pass through assigned through holes 27a, 27b in the punching knife and the assigned recesses (not shown) are countersunk in the bearing section of knife carrier 21.

An important aspect is that a tuning element in the form of a relatively thin tuning disk 29 ( Figure 3 ) is arranged. The adjusting disk 29 also has through holes through which the fastening screws 26a, 26b pass. The screwing of the punching knife 25a, 25b to the seat surface 28 thus simultaneously causes the adjusting disk 29 to be clamped between the seat surface 28 and the punching knife 25a.

As in particular in Figure 3 shown, the punch knife 25a, 25b has a knife base 30 on which, as in particular in FIGS Figures 4 to 6 shown, the through holes 27a, 27b are located, which penetrate the knife base 30 transversely to the lifting direction 15.

The punch knife also has a cutting wedge 31 which tapers to a cutting edge 32 in the stroke direction.

As in particular in Figure 3 As shown, the cutting wedge 31 is formed by a wedge inner surface 33 and a wedge outer surface 34, the wedge outer surface 34 in the example being oriented inclined to the stroke direction 15, while the wedge inner surface 33 runs essentially parallel to the stroke direction.

As also in Figure 3 As shown, the die 14 has a knife cavity 35 which has a die edge 36 associated with the wedge inner surface 33, the wedge inner surface 33 during the punching stroke at a certain distance that is determined by the thickness of the shim 29 transversely to the stroke direction , moved along the die edge 36.

As in particular according to the first embodiment in FIGS Figures 4 and 5 As shown, the cutting edge 32 of the punching knife 25a is contoured in such a way that it has an edge section 37a, 37b which is inclined with respect to a reference line 38 at right angles to the stroke direction 15.

As in particular in the Figures 4 and 5 As shown, the cutting edge 32 according to the first exemplary embodiment has two edge sections 37a, 37b which are arranged at an angle to one another and which together form a wedge shape. As a result, a wedge tip 40 or cutting tip is formed approximately centrally with respect to the edge length 39, which first hits the film element 12 to be processed during the punching stroke.

The characteristic contour of the cutting edge 32 according to the first exemplary embodiment is expediently produced in the manner of a diamond cut. As in particular in Figure 4 or 5, in this case not only is the cutting edge 32 ground with the two edge sections 37a, 37b, but the cut also merges into the outer surface 34 of the wedge. For example, two open areas 41a, 41b which also converge in a wedge shape are formed here.

As also in Figure 4 As shown, the knife cavity 35 is adapted to the contour of the cutting edge 32. In this case, the knife cavity 35 has two cavity sections 42a, 42b arranged at an angle to one another ( Fig. 4 ).

the Figure 6 shows a second exemplary embodiment of the punching tool 11 according to the invention. The second exemplary embodiment differs from the previously described first exemplary embodiment in the different configuration of the punch knife 25b, which in this case has a differently contoured cutting edge 32. In this case, the cutting edge 32 has a plurality of edge sections 37 which together form a wave-shaped contour. This can be achieved, for example, in the manner of a "bread knife sharpening".

As in particular in Figure 3 shown, the cutting wedges 31 of the punching knives 37a, 37b in the processing position dip into the film element 12 to be processed and, depending on their immersion depth, generate a cutting line 43 or a break line 44 in the film system 12 along an edge length of the cutting edge 32 Punch knives 25a, 25b are used by a height adjustment device (not shown) belonging to the punch unit 13. Using the height adjustment device, the punching knives 25a, 25b can be moved between a cutting height 45, in which the punching knives 25a, 25b generate a cutting line 43 during the punching stroke, and a perforation which is further away from the die 14 compared to the cutting height 45 in the starting position 16. Altitude 46, in which the punching knives 25a, 25b generate a breaking line during the punching stroke. In the case of punching knives 25b with a wave-shaped contour, these are also suitable for forming breaking lines 44.

The height adjustment device is a control device (not shown), via which an individual control of the punching knife modules 19 is possible in order to move them optionally into the cutting height position 45 or the perforation height position 46. As a result, a very different grouping of punching knives that generate cutting lines 43 and punching knives that generate perforation lines 44 can be set in order to make up the film element to be processed in completely different ways. The height adjustment unit can, for example, have a switching system by means of which the height of the punching knife modules 19 can be adjusted fluidically, for example pneumatically.

As in particular in Figure 7 shown, the height adjustment device comprises height adjustment units, of which in Figure 7 one is shown as an example. The height adjustment units 47 include the above-described base body 20 of the punching knife module 19 on which the knife carrier 21 is movably mounted via an adjustment drive 48, which also belongs to the height adjustment unit 47, specifically in the stroke direction 15. In the example shown, the adjustment drive 48 is designed as a spindle drive .

The punch unit 13 also includes further functional units. The punch unit 13 has a hold-down device 49 with at least one hold-down device, which fixes the film element to be processed in the processing position 17 on the die 14.

Furthermore, the punch unit 13 comprises several, in the example star-shaped, contour punches 50 for punching out a surface section 60 ( Fig. 8 ) of the film element to be processed 12. As in particular in Figure 1 As shown, a respective contour punch 50 is arranged between adjacent punching knives 27a, 27b. In the starting position 16, the undersides 51 of the contour punches are positioned closer to the die 14 than the cutting edges 32 of the punching knives 25a, 25b. The contour punches 50 thus rush ahead of the punching knives during the punching stroke and penetrate the plastic material of the film element 12 in front of the punching knives 25a, 25b. As in particular in the Figures 1 to 3 As shown, the die 14 has several contour cavities 52 which interact with the associated contour punches 50 during the punching stroke and into which the contour punches 50 can be moved, the contour cavities each adjoining adjacent knife cavities 35 for the punching knives 25a, 25b. As in particular in Figure 4 As shown, the contour cavities 52 are each bordered by support sections 53 which support the film element 12 to be processed. A step 54 is formed between the support sections 53 and the knife cavities.

Another functional unit of the punch unit 13 is a stop element 55 arranged on the base plate 18, which interacts with a counter-stop element 56 arranged on the die 14 in such a way that the stop element 55 located on the movable punch unit 13 to limit the punching stroke to the counter-stop element 56 hits. As in particular in Fig. 1 Several pairs of stop elements 55 and counter-stop elements 56 are shown distributed over the area of base plate 18 on the one hand and die 14.

An essential aspect is that, prior to the first use of the punching tool, the distance between the wedge inner surface 33 and the die edge 36 of each individual punching knife 25a, 25b can be precisely adjusted by means of appropriately selected adjusting disks 29. This distance does not have to be readjusted when the punching tool 11 is in operation. The punching knives 25a, 25b can be exchanged, for example in the event of wear, but the shims remain in place so that the correct distance between the wedge inner surface 33 and the die edge 36 is always set even with the newly installed punching knives.

During operation, it is first determined which packaging is to be given to the plastic-based film element 12 to be processed. A grouping of four, for example four yoghurt pots, is mentioned here as an example, but these are still connected at break lines 44 and can then be separated from one another by tearing them off.

Depending on the assembly task, groups of punching knives are then moved to the cutting height 45, so that a cutting line 43 is generated during the punching stroke and other groups are moved to the perforation height 46, so that breaking lines 44 arise here during the punching stroke. During the punching stroke, the punch unit 13 moves with the punch knives 25a, 25b correctly positioned in the height position downwards in the direction of the die 14 on which the film element 12 to be processed was previously placed.

Because the edge sections 42a, 42b of the cutting edges 32 of the punching knives 25, 25b are oriented obliquely to a reference line 38 oriented perpendicular to the stroke direction, the cut is not carried out simultaneously over the entire edge length, but gradually. For example cuts In the first exemplary embodiment, first insert the wedge tip 40 into the material of the film element 12. The cutting line 43 is therefore produced in the manner of a drawing cut, which considerably reduces the forces on the punching knives 25a, 25b.

During the punching cut, the punching knives 25a, 25b move into the assigned knife cavity 35 in the die 14. Downstream of the punching knives, the punching knives 25b located in the perforation height position 46 move into the film element 12 to be processed, but do not plunge so deeply, as a result of which the already described breaking line 44 arises.

The contour punches 50 have already moved into the film element 12 to be processed in front of the punching knives 25a, 25b and have punched out a, for example, star-shaped surface section 60. Because the cutting line 43 is formed over the entire cutting edge 32 of the punching knife, the transition between the punched-out surface section 60 and the cutting line 43 has no disruptive transitions, for example barb-like material residues. This is also supported by the fact that the film element 12 to be processed is supported in the area of the contour cavities 52 by the adjoining support sections 53.

Claims (15)

Punching tool for cutting plastic-based film elements (12), with a punch unit (13) which has a plurality of knife carriers (21), on each of which at least one punching knife (25a, 25b) tapering to a cutting edge (32) is attached, and with a die (14) assigned to the punch unit (13) and opposite it for receiving the film element (12) to be processed, the punch unit (13) opposite the die (14) in a stroke direction (15) Punching stroke is mounted relatively movably between a starting position (16) and a processing position (17), the cutting wedges (31) of the punching knives (25a, 25b) in the processing position (17) dipping into the film element (12) to be processed and depending on the depth of immersion along an edge length of the cutting edge (32) generate a cutting line (43) or a breaking line (44) in the film system (12), thereby k indicates that the cutting edges (32) of the punching knives (25a, 25b) are contoured so that they each have an edge section (37; 37a, 37b) which is inclined with respect to a reference line (38) at right angles to the stroke direction (15). Punching tool according to Claim 1, characterized in that the cutting wedges (31) are each formed by a wedge inner surface (33) and a wedge outer surface (34) and the die has a knife cavity (35) which is one of the wedge inner surfaces (33) has associated die edge (36), the wedge inner surface (33) moving along the die edge (36) at a certain distance transverse to the stroke direction (15) during the punching stroke. Punching tool according to Claim 1 or 2, characterized in that the cutting edge (32) has two edge sections (37a, 37b) which are arranged at an angle to one another and which together form a wedge shape. Punching tool according to Claim 1 or 2, characterized in that the cutting edge (32) has a plurality of edge sections (37) which together form a wave-shaped contour. Punching tool according to Claim 1 or 2, characterized in that the cutting edge (32) has a plurality of edge sections which together form a zigzag-shaped contour. Punching tool according to one of the preceding claims, characterized in that the punching punch unit (13) has several, for example star-shaped, contour punches (50) for punching out a surface section of the film element (12), the underside (51) of which in the starting position (16) is closer to the die (14) ) are positioned as the cutting edges (32) of the punching knives (25a, 25b). Punching tool according to one of the preceding claims, characterized in that the punching knives (25a, 25b) are each detachably fastened to a knife seat (24) of the associated knife carrier (31) by means of fastening means, the fastening means being in particular disk-shaped between the knife seat (24) and the wedge inner surface (33) arranged tuning element for adjusting the distance between the die edge (36) and the wedge inner surface (33). Punching tool according to one of the preceding claims, characterized in that the punch unit (13) has a height adjustment device for adjusting the height of the punching knives (25a, 25b) between a cutting height position (45) in which the punching knives (25a, 25b) form a cutting line ( 43) and a perforation height position (46) further away from the die (14) compared to the cutting height position (45) in the starting position (16) in which the punching knives (25a, 25b) generate a breaking line (44) during the punching stroke , having. Punching device according to claim 8, characterized in that the height adjustment device is assigned a control device for the individual control of the punching knives (25a, 25b) in order to move them optionally into the cutting height position (45) or the perforation height position (46). Punching tool according to Claim 8 or 9, characterized in that the height adjustment device has height adjustment units (47) for individually adjusting the height of the punching knives (25a, 25b) with respect to the die (14), the height adjustment units (47) preferably each having a base plate ( 18) of the punch unit (13) have connected base body (20) on which the knife carrier (21) with the punch knife is movably mounted in the stroke direction (15) via an adjusting drive (48). Punching tool according to Claim 11, characterized in that the adjusting drive is designed as a spindle drive. Punching tool according to one of the preceding claims, characterized in that the punch unit (13) has a hold-down device (49) with at least one hold-down device which fixes the film element (12) to be processed in the processing position (17) on the die (14). Punching tool according to one of the preceding claims, characterized in that the punch unit (13) has at least one stop element (55) to which at least one counter-stop element (56) on the die (14) is assigned in such a way that during the punching stroke to limit the stroke of the punch unit (13) the stop element (55) strikes the counter-stop element (56). Punching tool according to one of Claims 6 to 14, characterized in that the die (14) has at least one contour cavity (52) which interacts with the associated contour stamp (50) during the stamping stroke and into which the contour stamp (50) can be moved, the contour cavity ( 52) adjoins adjacent knife cavities (35) for the punching knives (25a, 25b). Punching tool according to Claim 15, characterized in that the contour cavities (52) are each bordered by support sections (53) which support the film element (12) to be processed.

Images